“Ice” (also sometimes called “crystal”) is MA of high purity. It can be found in the form of translucent to white shards as well as powder. Such MA is typically smoked, in part because high purity methamphetamine vaporizes at a relatively low temperature.[1,2] Also MA powder of high purity (which tends to be coarse) can be uncomfortable to snort, as the granules sometimes remain sharp enough to cut nasal passages.[3]

References

(1) Cho A. Ice: a new dosage form of an old drug. Science 1990 Aug 10;249(4969):631-4.